Histological changes in respiratory epithelium of right and left nasal cavities to Capsaicin in rat nasal mucosa

Nasal cycle, rhinitis and ipsilateral nasal polyps are seen in many Individuals. These effects are caused by changes made by vascular and neural tone releasing some neurohormones and vasoactive substances.Recently possible contribution of inflammatory mediators in nasobronchial reflexes have been reported by some studies. Their exact mechanisms are not determined yet.

One hundred fourteen male N-MRI rats have been divided as control and inflammation test groups in the groups of six rats. Severity of inflammation was measured 6 (acute) and 24 (chronic) hours after insertion of micropads- moistured with saline or 50 & 100μg Capsaicin- into nasal middle turbinate. For the assessment of the inflammation and its mechanism, intraperitoneal (i.p) injection of 2 & 5 mg/kg Monteluckast (common Luckotrien receptor antagonist) was applied.

Saline (control) compared to intact group caused significant increase in mucus secretion of right (R) and left (L) nasal cavities (28 & 36µl, respectively) (P<0.01 & P<0.05) and bronchial eosinophil count (22.5 & 17 (P<0.05). Different doses of capsaicin (50 & 100µg) compared to control group caused significant increase in right (17.43 & 23.5µl (P<0.001) and left (7.78 & 14.1 µl (P<0.001) mucus secretion, respectively. Bronchial eosinophils also was increased significantly in response to different doses of capsaicin in Right (11.3 & 16.7 (P<0. 01 & P< 0.001), and Left (9.2 & 16.64 (P<0.05 & P<0.01) respectively in chronic phase. Monteluckast (5 mg/kg i.p) significantly decreased capsaicin-induced mucus secretion of R & L nasal cavities (41.2 & 35.5µl) respectively (P<0.001) and bronchial eosinophils (7.3 & 5.5 respectively (P<0.001).

It is concluded that the Luckotriens have significant role in pathogenesis of upper air ways- mediated inflammation of respiratory disorders and that different results with left & right nasal cavities might be due to different autonomic innervations of these cavities.